In the early 1980s, W. Burgdorfer and colleagues were the first to culture the causative agent of the disease, at that time designated Lyme disease, from ticks in an area where it was endemic. Borrelia burgdorferi has been shown to survive in the extracellular matrix, hiding from host immune responses and allowing for long-lasting infection. Coinfections with other tick-borne pathogens can occur; culture could be hampered by antibiotic treatment, and inhomogeneous distribution of the bacterium through infected tissues could affect the chance to obtain positive cultures. The course of Lyme borreliosis in experimentally infected dogs was first described by Appel and colleagues. The objective clinical manifestations of Lyme borreliosis are similar worldwide, but there are regional variations, especially between the symptoms found in the United States, where Lyme borreliosis is exclusively caused by B. burgdorferi, and those found in Europe, where Lyme borreliosis is primarily caused by B. afzelii and B. garinii, but also B. burgdorferi . Erythema migrans is the most frequent clinical sign several days to weeks after B. burgdorferi infection and can be clinically diagnosed. Lyme borreliosis has become the most common vector-borne disease in the United States and Central Europe.

The number of reported annual cases of Lyme borreliosis in the United States from 1991 to 2006. Patients were reported to the Centers for Disease Control and Prevention from 1991 to 2006, and cases were defined using stringent case definitions (11). Numbers are likely to be an underestimation (167). (The figure is published courtesy of the CDC.)

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Figure 2.

The number of reported annual cases of Lyme borreliosis in the United States from 1991 to 2006. Patients were reported to the Centers for Disease Control and Prevention from 1991 to 2006, and cases were defined using stringent case definitions (11). Numbers are likely to be an underestimation (167). (The figure is published courtesy of the CDC.)

39. Cadavid,D.,, T.O’Neill,, H.Schaefer, and, A.R. Pachner.2000.Localization of Borrelia burgdorferi in the nervous system and other organs in a nonhuman primate model of lyme disease.Lab. Invest.80:1043–1054.